Police say that Jessica Lynn Howell, a 25-year-old O'Fallon mother, encouraged her boyfriend to rape her infant daughter -- prompting a brutal sexual assault that resulted in her four-month-old baby's death last year.

The woman was allegedly aware that her boyfriend, Jordan Lafayette Prince, 25, intended to assault her daughter, Ashlynn Lilith Peters, who did not survive the attack in December. Officials say they have text messages between the two that clearly demonstrate her responsibility in her child's death.

"These text messages [from the mother] encouraged the killer to engage in sexual conduct with the child," St. Charles County Prosecutor Tim Lohmar tells Daily RFT. "We're very confident that she was fully aware of the gravity of what it was she was suggesting."

The formal complaint filed Monday -- on view below, with graphic detail about the assault -- says that months prior to her baby's death, Howell and Prince sent implicating texts. The charges reference "communications with Prince suggesting a willingness to allow him to engage in sexual activity with Ashlynn."

Howell, already facing a child-endangerment charge, is now facing second-degree murder and child abuse charges. Her boyfriend was charged in December with second-degree murder and he reportedly told cops at the time that he had become frustrated with the baby because she wouldn't stop crying. In response, he allegedly choked the Ashlynn to death.

Jordan Prince.

The subsequent investigation and autopsy, however, revealed that the situation was much worse. The four-month-old had not only been strangled to death, but had also suffered from internal bleeding injuries caused by sodomy. That horrible discovery led cops to add an additional sexual-assault charge against Prince.

As if the case could not get any more gruesome and unbelievable, this week, the new charges against the mother imply that she was very much complicit in her daughter's rape.

"Anytime you've got a child victim, it's a terribly tragic situation," Lohmar tells us. "What makes this more disturbing is that the one person who should be there to care for the child, her mother, was indirectly responsible for her death."

The complaint says that the baby was killed by asphyxiation and that she suffered hemorrhages to her face, neck, chest and back and blunt force trauma to her head, causing a laceration to her ear and a hemorrhage near her skull. Further, the injuries from the sexual assault were severe enough that they would have caused her death even if she had not been strangled, the charges say.

Ashlynn would have turned one next month.

It's unclear what exactly Howell may have admitted to cops at this point, but Lohmar says, "Through the course of the investigation, which included interviews with her, we're very confident in our charges."

Howell also allegedly knew that Prince had previously been found guilty of committing a sex offense against a minor.

"She still allowed the child to be in his presence and under his care," Lohmar says.

Howell is being held on a $1 million cash-only bond and will eventually face trial later this year or in early 2014.

A Facebook page that seems to be some sort of memorial fund for the baby girl includes a comment from what appears to be Jessica Howell's account back in January: